Pneumatic grinder

ABSTRACT

The present invention provides a pneumatic grinder connected to a driving gear or spindle at the tip end of the coupling shaft, in which a bearing is set upon the front portion for anti-eccentric-shaking, improving the concentricity of the grinder, in order to suit higher running speed smoothly and higher gearing accuracy; the coupling mechanism of the tilting head and the main body is simplified into a single component—retaining cover having two counter revolving oriental threads for securing, meanwhile the sizes of said main body and the driving gear are shortcut; the rotor and the shoots on it are formed in a single process in the injection casting simultaneously, in order to improve manufacturing speed and reduce cost.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a pneumatic grinder, and moreparticularly to a reformed structure of a pneumatic grinder, by changingpneumatic motor's structure and positions of bearings.

[0003] 2. Description of Prior Art

[0004] In accordance with the conventional pneumatic grinder in themarket so far, the most of them are divided into two kinds—tilting headtype (as shown in FIG. 1 and FIG. 2) and straight type (as shown in FIG.3 and FIG. 4) in the grinding head structure, therein their drivingstyles are almost same, the only a bit difference is on the cramping wayof the grinding component; the energy of driving spinning is to take theadvantage of compressed air led in from the inlet 11 or 21, then via airvalve 12 or 22 the compressed air enters said pneumatic motor 13 or 23to push the blades 14 or 24 to move, and simultaneously to bring uprotor 15 or 25 spinning; said pneumatic motor 13 or 23 has a front cover131 or 231 and a back cover 132 or 232, in which a pair of bearings 133,233 and 134, 234 bear up said rotor 15 or 25 from the coupling shaft 151or 251 and the locating shaft 152 or 252 separately; but whatever theconventional pneumatic grinders in the both structures may generateeccentric vibration and be poor concentricity as follows:

[0005] 1. Tilting Head Pneumatic Grinder:

[0006] Referring to FIG. 1 and FIG. 2, a conventional tilting headpneumatic grinder 10 is shown, in which said pneumatic motor 13 isretained by securing a retaining ring 16 on the tip end of said mainbody 17 for tightly pushing the front surface of said front cover 13,for driving the grinding head or locating said front bearing 133 inplace, a driving gear 18 is secured on the tip of said coupling shaft151, and simultaneously to press tightly the terminal end of saidbearing 133, meanwhile the teeth portion of said driving gear 18 isextended into the inside of the tilting head 19 for gearing to thespindle gear 192 of the spindle 191, and said tilting head 19 and saidretaining ring 16 are fastened on tip end of said main body 17 bysecuring a retaining cover 171; by driving said pneumatic motor 13 tospin, via gearing transportation of said driving gear 18 and saidspindle gear 192, said spindle 191 can spin at 20000 r/min. at least,further to drive the grinding tool 193 to spin in high speed.

[0007] In above-mentioned driving mechanism, the driving gear 18 mayoften generate shake and poor gearing condition with the spindle gear192 so that the whole body is shaken and striking phenomenon happensbetween the both gearing gears to bring up poor running further toshortcut service life; the explored sake is that the suspended length(about 39 mm) of said driving gear 18 from the front end of said bearing133, meanwhile because this length includes the front cover 131,retaining ring 16 locating said front cover 131, the flange of saidtilting head 19 and the retaining cover 171 securing said tilting head19 and retaining ring 16 in architecture, so the suspending length ofsaid driving gear 18 is unable to be cut shorter, therefore over lengthmust create shaking phenomenon, meanwhile the suspended driving gear 18without any support has to generate shake phenomenon at the tip endunder the high speed spin.

[0008] On the other hand, the coupling connection of said driving gear18 and the tip end of said coupling shaft 151 is designed into securejoint, in which the back lash must be existed in securing connection,and when the combined central axis has a bit of deviation, the eccentricrotation may be happened, especially at high speed spinning strikingphenomenon must be occurred. Therefore, the engaging friction andinterruption phenomena between said driving gear 18 and said spindlegear 192 may be occurred by said shake caused by eccentric spin, oversuspending length of said driving gear 18 and gearing deviation, so asto create over laude of noise, affect the output power of the spindle191 relatively, and increase relatively product percent defective.

[0009] The said driving mechanism is belong to small power device, whenoutput power is increased, the sizes of every part may be increased toorelatively, the length of said driving gear 18 is relatively increased,so that the spinning deviation and shaking scales must be increased too,the strike and noise are relatively improved too, therefore any samesized pneumatic grinder outputting relative bigger power has not turnedout. Additionally, for fastening said tilting head 19 on the main body17, via two parts—said retaining ring 16 and said retaining cover 171,the combination process is divided into two steps for finishing, and theparts may take much manufacturing time (especially cutting inner andouter threads) relatively, the production cost may be relativelyincreased; this assembly mechanism—via two parts must occur lengthincreasing, this is main sake of causing over length of the driving gear18.

[0010] 2. Straight Head Pneumatic Grinder:

[0011] A conventional straight head pneumatic grinder 20, referring toFIG. 3 and FIG. 4, is shown, wherein the pneumatic motor 23 is locatedby the securing retaining ring 26 via the front cover 231, then securethe retaining cover 271 for fastening; the coupling shaft 251 is securedwith the spindle 28 at the tip end directly, via a clamping nut 281 saidspindle 28 is connected to a grinding tool 29, so it is obvious that thefront cover 231 and the back cover 232 are not fastened tightly axiallyin the inside of the main body 27 besides the retaining ring 26, butsecuring connection exists a bit of back lash, therefore when at highspeed spinning shake may be easily created, and the coupling shaft ofthe rotor 25 is suspended out of the front bearing 233 of the frontcover 231, and secured to the spindle 28, so the securing joint portionmay have error of concentricity existing so that the spindle 28 runningat high speed (20000 r/min.) may bring all the parts on it to eccentricshaking, additionally plus the shaking coming from the front and backcovers 231 232, the shake is enough big to affect the concentricity andcutting accuracy of said grinding tool 29, this is a vital sake that therunning speed can not be further improved.

[0012] 3. Shortcomings of the Rotor Mechanism:

[0013] Referring to FIG. 1 to FIG. 4, the conventional rotor 15 or 25 ismanufactured by turning the coupling shaft 151 or 251 segment, the shootshaft 153 or 253 segment and the locating shaft 152 or 252 firstly, thenmilling shoots 154 or 254; when milling cutting shoots 154 or 254,because they are narrow and deep, the milling tool has to keep in asmall amount of feed at a low speed, and every rotor 15 or 25 has 4 to 6shoots 153 or 253 (depending on the output power and rotation speed),therefore the cutting efficient of the shoots 154 or 254 is becameobvious, and the production cost is quite high; on the other hand, forfacilitating milling, the shoots 154 or 254 cut into said shoot shaft153 or 253 from the terminal end at the coupling shaft side are inopening state, then turning a block ring 155 or 255 putting on thecoupling shaft 153 or 253 for blocking the opening grooves; inassembling, said blocking ring 155 or 255 is placed between the frontcover 131 or 231 and the shoots 153 or 253 for preventing they fromfriction.

OBJECTS AND SUMMARY OF THE INVENTION

[0014] It is therefore a main object of the present invention to providea pneumatic grinder connected to a driving gear or spindle at the tipend of the coupling shaft, in which a bearing is set upon the frontportion for anti-eccentric-shaking, improving the concentricity of thegrinder, in order to suit higher running speed smoothly and highergearing accuracy.

[0015] It is a next object of the present invention to provide apneumatic grinder, in which the rotor is made of magnesium-aluminumalloy, aluminum alloy, zinc alloy, tin or plastic by injection castingfor simplifying procedure and reducing manufacturing costsimultaneously.

[0016] The third object of the present invention is to provide apneumatic grinder, in which the rotor and the shoots on it are formed ina single process in the injection casting simultaneously, in order toimprove manufacturing speed and reduce cost.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a sectional view of a conventional tilting headpneumatic grinder.

[0018]FIG. 2 is an exploded view of the conventional tilting headpneumatic grinder.

[0019]FIG. 3 is an exploded view of a conventional straight headpneumatic grinder.

[0020]FIG. 4 is a sectional view of the conventional straight headpneumatic grinder.

[0021]FIG. 5 is an exploded solid view of the present invention.

[0022]FIG. 6 is a sectional view of the present invention.

[0023]FIG. 7 is an exploded solid view showing the retaining ring in theembodiment of the present invention.

[0024]FIG. 8 is a sectional view showing the retaining ring in theembodiment of the present invention.

[0025]FIG. 9 is a sectional view showing a straight head pneumaticgrinder in the second embodiment of the present invention.

[0026]FIG. 10 is a sectional view showing the stone cutting applicationembodiment of the present invention.

[0027]FIG. 11 is an exploded solid view showing the rotor of the presentinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0028] Referring to FIG. 5 and FIG. 6, a pneumatic grinder 30 providedof the present invention is comprised of a main body 31 having a shafttube with a bearing housing 310 at the back end for holding in a bearing341, a pneumatic motor 32 loaded into the inside of said main body 31wherein a rotor 33 of said pneumatic motor 32 is located in place byfitting the back end locating shaft 332 into said bearing 341, andputting a ring 35 embedded into a front cover 36 and a bearing 39sequentially on the front coupling shaft 331, and a retaining cover 37securing on the front end of said main body 31 with one end so that aninside housing 371 of said retaining cover 37 holds said front cover 36and via it to locate axially said pneumatic motor 32, a driving gear 38secured on the thread portion at the front tip end of said couplingshaft 331 and fit into said bearing 39 with the back small end forlocating, and said bearing 39 housed at front end of the inside of thetilting head 40 so as to keep the concentricity of said tilting head 40and said coupling shaft 331, said tilting head 40 connected with theretaining cover 37 by securing the thread portion 401 to the innerthreaded hole 372, in the said retaining cover 37 the inner thread ofthe hole 372 having a counter rotary thread with the outer thread on itso that the tilting head 40 can be rotated in any angle as un-securingup the retaining cover 37, thereby as screwing said retaining cover 37into the main body 31 to retain the front cover 36, simultaneously tofasten the tilting head 40 and to gear the driving gear 38 to thespindle gear 42 located on the spindle 41 for driving the spindle 41 inhigh speed simultaneous spinning.

[0029] In accordance with above-mentioned, the present invention hassome feathers as follows:

[0030] 1. Stable Driving Gear:

[0031] Referring to FIG. 5 and FIG. 6, the driving gear 38 is fittedinto the inside of the bearing 39, meanwhile the bearing 39 is locatedon the coupling shaft 331 and in the inside of the tilting head 40, sothe driving gear 38 is got to be supported directly without overlongsuspending length, and the concentricity of the located position isgreatly improved, even if running under high speed, the eccentricshaking phenomenon will not happen, simultaneously the gearing accuracyis improved, and relatively to improve transmission efficient andservice life.

[0032] Referring to FIG. 9 and FIG. 10, a straight head type embodimentof the present invention is shown, wherein the spindle 63 of thestraight head pneumatic grinder 60 or the spindle 72 of a stone cuttingmachine 70 is fitted into the bearing 39 directly as same as the way ofsaid driving gear 39 with the small end 631 or 721 for locating thecoupling shaft 621 and the spindle 63 or 72, meanwhile improving theaccuracy of concentricity, even if running under high speed, theeccentric shaking phenomenon will not happen, simultaneously the gearingaccuracy is improved, and relatively to improve transmission efficientand service life.

[0033] 2. Simplifying the Coupling Mechanism of the Tilting Head and theMain Body:

[0034] The coupling mechanism is simplified relative to theconventional—from two components to only one—retaining cover 37, asshown in FIG. 5 and FIG. 6, taking the advantage of two couple ofdifferent revolving oriental inner and outer threads instead of theconventional three to finish coupling the tilting head 40 to the mainbody 31, so the thread cutting cost and component cost are saved,meanwhile in combination the single component—retaining cover 37 makesthe assembly process simple and rapid, and the combination andmanufacture cost are reduced too.

[0035] Additionally, referring to FIG. 9 and FIG. 10, the retainingcover 66 replaces the conventional two components—retaining ring 26 andthe retaining cover 271 as shown in FIG. 3 and FIG. 4, as same asabove-mentioned to simplify components, to make the assembly processsimple and rapid, and to reduce the combination and production costs.

[0036] 3. Shortcutting the Driving Gear:

[0037] Due to simplifying the coupling mechanism of the tilting head 40and the main body 31 into a single component—the retaining cover 37, andloading the bearing 39 on the driving gear 39 directly, and simplifyingthe structure and shape of the front cover 36 and back cover 34, both ofthe thicknesses are decreased, the front cover 36 is pushed by theretaining cover 37 from the terminal side to locate the pneumatic motor32 in the inside of the main body 31, it not only shortcuts the wholelength of the main body 31, but also the length of the driving gear 38is also shortcut relatively (about 8˜15 mm) and the rigidity isimproved, so that the tip end of it will not shake even under highrunning speed, and simplifying and shortcutting every components makesthe part production cost reduce relatively and improve the productioncompetition in the market.

[0038] Additionally, referring to FIG. 7 and FIG. 8, in this embodimentthe retaining cover 50 couples and fastens the tilting head 40 on themain body 31 by securing on the outer thread 311 on the tip end of themain body 31 and outer thread of the tilting head 40 respectively withthe inner different revolving oriental threads 51 52, in the same way toget fastening and simplifying component function.

[0039] 4. Innovation Method of Manufacturing Rotor:

[0040] a.) The rotor 33, as shown in FIG. 5, is made ofmagnesium-aluminum alloy, aluminum alloy, zinc alloy, tin, and molded ininjection casting to get shaped rotor 33 including shoots 33 directly,then turning the both ends—the coupling shaft 331 and locating shaft 332and the ring 35, and the forcing slots 334 are molded on the outersurface of the rotor 33, not only reduce the weight of the rotor 33, butalso increase the front face area, besides the blades 335 receive thepushing pressure of the compressed air, the forcing slots 334 alsoaccept the drive coming from the compressed air so that the front facearea of the rotor 33 is increased, therefore the rotor 33 creates thepower relatively to be gone up coordinately.

[0041] b.) Referring to FIG. 11, the coupling shaft 81, the space ring82, and the locating shaft 83 of said rotor 80 can be obtained byturning in a whole piece, in this way the steel material is used in asmall size so that the production cost is lower, the segment between thespace ring 82 and the locating shaft 83 may be cut into polygon bar 84(or other shapes, or surface indentation treatment); and the shoot shaft85 and the shoots 851 are molded in injection casting directly, it ismade of magnesium-aluminum alloy, aluminum alloy, zinc alloy, tin; ormade of plastic in injection molding directly without milling shoots851, so that the process of manufacturing rotor 80 is simple and rapid,and the production cost of it is efficiently reduced.

[0042] The present invention can be applied into variety pneumatic toolmachine, just as straight head pneumatic grinder, tilting head pneumaticgrinder, pneumatic stone cutting machine, pen type pneumatic grinder andso on, and other fields in the range of utilizing this technology.

I claim:
 1. A pneumatic grinder, comprised of a main body housing apneumatic motor at the inside from the front end, by fitting thelocating shaft of the rotor into the back bearing at the inside of themain body, and a space ring put on the coupling shaft at the front endof said rotor, and a front cover holding said space ring at the inside,and the retaining cover securing on the front tip end of said main body;wherein, said retaining cover has an inner housing for holding saidfront cover in and pushing and locating said pneumatic motor in place,the coupling shaft has a thread portion built on the tip end forsecuring the driving gear, which is located at the inside of said frontbearing with the small end for clamping and locating the bearing, saidfront bearing is located the inside of the tilting head with the outersurface for keeping the concentricity with said coupling shaft, and saidtilting head is secured on the inner threaded hole of said retainingcover with the outer thread portion, thereby as screwing said retainingcover into the main body to retain the front cover, simultaneously tofasten the tilting head and to gear the driving gear to the spindle gearlocated on the spindle for driving the spindle in high speedsimultaneous spinning.
 2. A pneumatic grinder as claimed in claim 1,wherein said main body has a shaft tube with a bearing housing at theback end for holding in a bearing in.
 3. A pneumatic grinder as claimedin claim 1, wherein said retaining cover has an inner thread at theinside hole and an outer thread at the external surface, the said boththreads have different revolving orient each other.
 4. A pneumaticgrinder as claimed in claim 1, wherein, the main body has an externalthread built on the outer terminal end, the retaining cover has twocounter revolving oriental inner threads for securing on the externalthreads of said main body and said tilting head to get locking functionas above-mentioned structure in claim
 3. 5. A pneumatic grinder asclaimed in claim 1, wherein, said rotor including shoots is shaped bymolding in injection casting directly.
 6. A pneumatic grinder as claimedin claim 1, wherein, the forcing slots on the surface of said rotor aremolded in injection casting directly.
 7. A pneumatic grinder as claimedin claim 1, wherein, the coupling shaft, the space ring, and thelocating shaft of said rotor can be obtained by turning in a wholepiece, the segment between the space ring and the locating shaft may becut into polygon bar, the shoot shaft and shoots are obtained by moldingin injection casting directly.
 8. A pneumatic grinder as claimed inclaim 1, wherein, said rotor including the shoot shaft and shoots ismolded in plastic injection mold.
 9. A pneumatic grinder as claimed inclaim 7, wherein, said rotor including the shoot shaft and shoots ismolded in plastic injection mold.